Answering Top-k Queries over Outsourced Sensitive Data in the Cloud

The cloud provides users and companies with powerful capabilities to store and process their data in third-party data centers. However, the privacy of the outsourced data is not guaranteed by the cloud providers. One solution for protecting the user data is to encrypt it before sending to the cloud. Then, the main problem is to evaluate user queries over the encrypted data. In this paper, we consider the problem of answering top-k queries over encrypted data. We propose a novel system, called BuckTop, designed to encrypt and outsource the user sensitive data to the cloud. BuckTop comes with a top-k query processing algorithm that is able to process efficiently top-k queries over the encrypted data, without decrypting the data in the cloud data centers. We implemented BuckTop and compared its performance for processing top-k queries over encrypted data with that of the popular threshold algorithm (TA) over original (plaintext) data. The results show the effectiveness of BuckTop for outsourcing sensitive data in the cloud and answering top-k queries.